PM Update: One storm out, another one in

It is often said in the meteorological world that “dry begets dry”. In this case, snow begets snow. Amidst a hemispheric pattern which has historically been unfavorable for snow, multiple snowstorms have driven through the Northeast United States over the past two weeks. Most recently, for obvious reasons, is the snowstorm which occurred just this past Saturday Night into Sunday and left a significant snowfall accumulation in many areas, especially Northern New Jersey, New York City and Southeast New York into Connecticut. But even prior to that, a rare significant December snowfall over Philadelphia and Central New Jersey got winter off to a surprisingly fast start.

Saturday and Sunday’s event was certainly the most significant so far on this young winter’s season, with a significant snowfall and then icing across the interior. It was also the most interesting from a mesoscale perspective, with a dramatic coastal front and mid level warm air advection changing areas over to sleet and freezing rain despite surface temperatures in the 20’s. Regardless, after several inches of snow most areas changed over to rain. The cold air held on longer inland, and was much quicker to scour out near the coast. You can access our official verification map, with plotted totals over our forecast, right here. Attention now turns to a clipper type storm system, which will swing through the area on Tuesday — and forecast models are beginning to hone in on the potential for another light snowfall.

High resolution NAM model showing a period of moderate snow throughout the area on Tuesday morning.

High resolution NAM model showing a period of moderate snow throughout the area on Tuesday morning.

With an active pattern in place across much of the Continental United States, it shouldn’t be terribly surprising that a few clipper systems are forecast to dive southeast from Canada through the Northeast US in the wake of our weekend storm system. But newer forecast models are coming into agreement on the surface low, associated with a mid and upper level disturbance, tracking just south of our area on Monday Night through Tuesday morning. Despite the progressive nature of the pattern, this could cause the development of a weak surface low south of Long Island. And such a development would all but certainly aid in the development of precipitation — likely falling in the form of snow across much of the area — early on Tuesday morning through the afternoon.

There are still a few concerns with the potential clipper system, however. First, the track of these systems historically trends north or northeast with time. This is something that forecasters in this part of the country can certainly attest to. And the progressive nature of the pattern may argue for less amplification, and a farther north and faster track. Second, the boundary layer remains warm despite the presence of very cold, arctic air aloft. In more simplistic terms, there is still some warm air near the surface despite very cold air well above our heads — it is a problem we will deal with more often than not. Such is life, living by the sea. We can see the warmer boundary layer on the NAM models forecast temperature on Tuesday. This could mean mixed precipitation or even rainnear the coast at times during the precipitation. Third, the fast pace of the system leaves little room for error — and so we err on the side of caution when it comes to snowfall accumulations.

NAM model showing the development of stronger lift across NYC, LI and CT as the coastal low develops on Tuesday.

NAM model showing the development of stronger lift across NYC, LI and CT as the coastal low develops on Tuesday.

In terms of sensible weather, we are forecasting increasing clouds on Tuesday as the system begins to trek towards the area from the Great Lakes. Snow will overspread the region late Monday Night into early Tuesday, beginning light with broken bands of more moderate snow. A burst of more steady moderate snow is possible later on Tuesday morning, with mixed precipitation possible on the shores of New Jersey and Long Island. As the system strengthens slightly in the Atlantic Waters, a burst of moderate snow is also possible over Connecticut and Long Island as the system begins to pull towards Southern New England. The system will begin to pull away by later on Tuesday, but forecast models are already hinting at another disturbance which may keep periods of snow going throughout New Jersey into Wednesday.

Stay tuned over the next several hours into early on Monday, as we continue to analyze new data and information.

Storm Total Snowfall forecast, valid through Wednesday evening.

Storm Total Snowfall forecast, valid through Wednesday evening.

 

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